A subcaliber projectile is a projectile whose body is smaller in diameter than the bore of the weapon, e.g. a cannon from which the projectile is to be fired. While the body of the projectile may be armed, i.e. include an explosive charge, considerable attention has been directed in recent years to inertial impact projectiles which are composed of a heavy metal and, in even more recent developments, may comprise several parts for successively penetrating the layers of armor of armored vehicles such as tanks and personnel carriers. The body is thus composed of or comprises a heavy metal, e.g. titanium, or composites of heavy metals.
Such bodies may be fin-stabilized, i.e. provided with fins which stabilize the flight of the projectiles as the projectile initially emerges from the weapon and following the separation of the sabot segments from the projectile body.
The sabot is in effect a self-releasing adapter between the relatively slender body of the projectile and the wall of the bore of the weapon so that the gases generated by the firing of a charge in the breech of the weapon will propel the projectile assembly from the mouth of the barrel along the desired trajectory. During flight, upon encountering air resistance, the segments of the sabot may be pulled away from their form-locking engagement with the body of the projectile and thus are lost as the fin-stabilized body continues on its flight to the target. The sabot is frequently also referred to as a drive cage.
Reference may be had to U.S. patent application Ser. No. 291,825 corresponding to German application DE-P 30 30 072.2, and U.S. Pat. No. 3,620,167, for example.
Form-locking means for ensuring an immobile connection between the drive cage and the projectile body have, of course, been provided heretofore. Such means can include threads or grooves formed on the exterior of the body of the projectile and engageable by complementary threads or ribs formfitting into them from the sabot. One of the difficulties with this approach, however, has been that the threads or grooves represent indentations in the body of the subcaliber projectile and can form weakened zones or incipient cracks which can spread upon impact and thereby decrease the penetrability of the projectile at the target.
In order to avoid the notching of the body of the projectile, illustrated, for example, in U.S. Pat. No. 3,620,167, the approach described in German application 30 30 072.2 was successfully adopted and utilized an additional element around the projectile body to create the formfitting connection with the sabot and exploit the metallurgical properties of this element and the projectile to immobilize the additional formfitting element on the projectile body. The formfitting element was preferably a one-piece sleeve of light metal such as an aluminum alloy.
While this approach was successful, it nevertheless required a somewhat complex relationship between the formfitting element and the heavy metal projectile body which could not always be obtained in practice.